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Moldavite

Moldavite (Czech: Vltavín) is an olive-green or dull greenish vitreous substance possibly formed by a meteorite impact. It is one kind of tektite. It was named[citation needed] by A. Dufrnoy for the town of Moldauthein (Czech: Týn nad Vltavou) in Bohemia (the Czech Republic), where it occurs. It is sometimes cut and polished as an ornamental stone under the name of pseudo-chrysolite. Its bottle-green glass color led to its being commonly called Bouteillen-stein, and at one time it was regarded as an artificial product, but this view is opposed to the fact that no remains of glassworks are found in the neighborhood of its occurrence; moreover, pieces of the substance are widely distributed in Tertiary and early Pleistocene deposits in Bohemia and Moravia. For a long time, it was generally believed to be a variety of obsidian, but its difficult fusibility and its chemical composition are rather against its volcanic origin. ...
(Wikipedia: http://en.wikipedia.org/wiki/Moldavite)

Moldavite – a mysterious stone 14.7 million years old, being rumored to carry fortune to its owner. The stone rise of which is circled in enigmas and a lot of theories. One of them describes a fall of huge body of several cubical kilometers bulk. Upon impact there arose a gigantic explosion comparable with multiple hydrogen bomb, atmosphere split and Moldavites (tektites) spawned within emerged vacuum bubble. Moldavites the look of which is exceedingly glamorous are colored in miscellaneous tints of green. It is used to be from light up to bright green, bottle-green, olive, vitriolic, and from brown-green to brown. Moldavites are of strong glass gleam, sometimes almost lacquer gleam. Moldavites’ sharps are weird – discs, balls, oval, drops, sticks, cylindrical sharps or irregular fragments. Ever before Moldavite’s surface attracted attention with its segmentation, with fine or rather bigger rounded or elliptical holes, occasionally wrinkled and eroded by the most romantic notches. Moldavites also hold attention by their not fully clear and mysterious origin. Thus, there’s no wonder they had become sought-after jewel stones.

Two-coloured moldavites are very rare between the Czechoslovak tektites.Recently further nine two-coloured moldavites were found in Southern Bohemia. Three of them were analyzed using an electron microprobe analyser. All the specimens are characterized on the basis of macro- and microobservations, i.e. colours and others optical properties, shapes, content of bubbles, number of lechatelierite grains. It may be stated that the colours of glass are the results of different chemical composition in differently coloured areas. The difference in colours appears to be caused by the total iron content, the Fe 2+/ Fe 3+ ratio, and partly also in MnO content. The sharpness of the contact between the differently coloured areas indicates that the two-coloured moldavite were at a high temerature for a very short time only.

SOUKENÍK (1964) was the first who has mentioned a two-coloured moldavite, an oblate spheroid of 3,74 grams, from Skryje in Moravia. The body of the specimen is light olive brown, but contains a small light green portion of several cubic mm. The boundary between both zones is quite sharp. Later, one additional also two-coloured cylindrical irregular moldavite fragment was discovered in the Soukeník‘s collection. It derives from the Mikulovice near Třebíč in Moravia. The body of the specimen is olive green but contains a small light green spot completely enclosed in the darker glass. In this case the boundary between the two coloured areas of glass appears diffuse.

The two-coloured moldavite from Lipí in Southern Bohemia has been described by BOUŠKA (1965) and two noteworthy finds of two-coloured moldavites from Kamenný Újezd and Slávče in Southern Bohemia have been given BOUŠKA and ROST (1972). In the latter case two moldavites are thrust into each other. The collision evidently took place during the flight of an inhomogeneous swarm of moldavites, still plastic with somewhat different viscosities corresponding to their size and chemical composition, but already displaying almost definite aerodynamic shapes before their infall to the earth’s surface, as otherwise they could have been shattered. The one with the sharper and probably more solidified surface is partly plunged into the other moldavite. The two-coloured moldavite from Kamenný Újezd is a quite unique example. One part of its drop shape, slightly olive green in colour, is plunged almost perpendicularly by its thicker end into the other moldavite which is flat oval and olive green. The junction of the two parts of the moldavite is anisotropic with relatively higher interference colours of the first order if examined between crossed nicols. The other parts of the joined moldavite display common anisotropy known in moldavites. The surficial sculpture is rather coarse in the main body and somewhat finer in the plunged drop. The schlieren and elongated vesicles in both parts of the moldavite are perpendicular to each other.

For the present, most detailed study was devoted to the specimen from Lipí (KING and BOUŠKA 1968). The main body of the moldavite is olive brown and only a small portion on the periphery of the specimen is light green. The colours are quite distinct and correspond well to the previously published moldavite colour scale of BOUŠKA and POVONDRA (1964). The microprobe traverse across the boundary between the light green and olive brown areas indicates that the transition between the areas of different composition (the difference in colour appears to be caused by the difference in total iron contect) is gradual and only about 20 microns wide.

The sharpness of the boundary between the light green and olive brown glass together with the relatively constant K2O content greatly, and the different CaO values indicate that fractional volatilization probably was not responsible for the difference in composition in this two-coloured moldavite, and also that the specimen was at a high temperature during its formation for a very short period of time, on the order of seconds or some minutes as a maximum.

The microprobe analysis of the specimen is presented and discussed together with our data. Recently, further nine two-coloured moldavites were found in Southern Bohemia and we could studied them in detail. Three selected were anylyzed using an electron microanalyzer.